A small body in the solar system that moves in orbit around the sun is called an asteroid. Asteroids are significantly smaller than planets in size and do not have their own atmosphere, although, like planets, they can have their own satellites. Asteroids are made of rocks and metals, mainly nickel and iron.
Term "asteroid" translated from Greek means "star-like"
. This name was coined by William Herschel, who noticed that through a telescope lens asteroids look like small points of stars. Planets are visible through a telescope as disks.
Until 2006, a synonym for the term “asteroid” was “minor planet”. Asteroids differ from meteoroids in size: the diameter of an asteroid must be at least thirty meters.
Sizes and motion of asteroids
The largest asteroids known today are (4) Vesta and (2) Pallas, with a diameter of about 500 kilometers. Vesta can be seen from Earth with the naked eye. The third large asteroid, Ceres, was reclassified as a dwarf planet in 2006. The dimensions of Ceres are about 909 by 975 kilometers.
According to scientists, there are between a million and two million asteroids larger than a kilometer in diameter in the solar system. 
Most of these celestial bodies are located in the belt between Jupiter and Mars, but individual asteroids can move in an elliptical orbit outside this belt, around the Sun. There is another well-known asteroid belt, not far from the orbits of Pluto and Neptune - the Coyer Belt.
Asteroids, as already mentioned, do not stand still; in the process of movement they can collide with each other and satellites. On the surface of planets and satellites that asteroids collided with, deep marks - craters - remain. The diameter of the crater can reach several kilometers. During a collision, relatively small fragments—meteorites—can break off from asteroids.
Origin and features
Scientists have been trying for a very long time to find an answer to the question - where do asteroids come from? Today, two versions are popular. According to one of them, asteroids are the remnants of matter from which, in fact, all the planets of the solar system were formed. Another theory suggests that asteroids are fragments of large planets that previously existed and were destroyed due to an explosion or collision. 
Asteroids are cold cosmic bodies. These are, in fact, huge stones that do not emit heat or reflect it from the Sun, since they are very far from it. Even an asteroid located close to the star, having heated up, will give off this heat almost immediately.
What are the names of asteroids?
The first asteroids discovered were named after ancient Greek mythological heroes and gods. By a strange coincidence, at first these were female names, but only an asteroid with an unusual orbit could count on a male name. Later, this trend gradually faded away.
In addition, the right to give asteroids any names was given to people who discovered them for the first time. Thus, today, whoever discovers a new asteroid can name it according to his own taste, and even call it by his own name.
But there are certain rules for naming asteroids. They can be given names only after the orbit of the celestial body has been reliably calculated, and until that time the asteroid is given a non-permanent name. The asteroid's designation reflects the date it was discovered.
For example, 1975DC, where the numbers indicate the year, the letter D is the number of the crescent in the year when the asteroid was discovered, and C is the serial number of the celestial body in this crescent (the asteroid given in the example was the third to be discovered). There are 24 crescents in total, and there are 26 letters in the English alphabet, so they decided not to use two letters - I and Z - when naming asteroids. 
If more than 24 asteroids are discovered in one crescent, the second letter is assigned an index of 2, the venture - 3, and so on. And after the asteroid receives an official name (and it happens that this takes more than one decade - all this time the orbit is being calculated), its name includes the serial number and the name itself.
An asteroid is a relatively small, rocky cosmic body similar to a planet in the solar system. Many asteroids orbit the Sun, and the largest cluster of them is located between the orbits of Mars and Jupiter and is called the asteroid belt. The largest known asteroid, Ceres, is also located here. Its dimensions are 970x940 km, i.e. almost round in shape. But there are also those whose sizes are comparable to dust particles. Asteroids, like comets, are remnants of the substance from which our solar system was formed billions of years ago.
Scientists suggest that more than half a million asteroids with a diameter greater than 1.5 kilometers can be found in our galaxy. Recent research has shown that meteorites and asteroids have similar compositions, so asteroids may well be the bodies from which meteorites are formed.
Asteroid exploration
The study of asteroids dates back to 1781, after William Herschel discovered the planet Uranus to the world. At the end of the 18th century, F. Xaver gathered a group of famous astronomers who searched for the planet. According to calculations, Xavera should have been located between the orbits of Mars and Jupiter. At first the search did not produce any results, but in 1801, the first asteroid was discovered - Ceres. But its discoverer was the Italian astronomer Piazzi, who was not even part of Xaver’s group. Over the next few years, three more asteroids were discovered: Pallas, Vesta and Juno, and then the search stopped. Only 30 years later, Karl Louis Henke, who showed interest in studying the starry sky, resumed their search. Since this period, astronomers have discovered at least one asteroid per year.
Characteristics of asteroids
Asteroids are classified according to the spectrum of reflected sunlight: 75% of them are very dark carbonaceous class C asteroids, 15% are grayish-siliceous class S asteroids, and the remaining 10% include metallic class M and several other rare species.
The irregular shape of asteroids is also confirmed by the fact that their brightness decreases quite quickly with increasing phase angle. Due to their large distance from the Earth and their small size, it is quite problematic to obtain more accurate data about asteroids. The force of gravity on an asteroid is so small that it is not able to give them the spherical shape that is characteristic of all planets. This gravity allows broken asteroids to exist as separate blocks that are held close to each other without touching. Therefore, only large asteroids that avoided collisions with medium-sized bodies can retain the spherical shape acquired during the formation of planets.
> Asteroids
All about asteroids for children: description and explanation with photos, interesting facts, what an asteroid and meteorites are, the asteroid belt, falling to Earth, types and name.
For the little ones It is important to remember that an asteroid is a small rocky object, devoid of air, orbiting a star and not large enough to qualify as a planet. Parents or teachers At school can explain to the children that the total mass of asteroids is inferior to that of Earth. But don't think that their size doesn't pose a threat. In the past, many of them crashed into our planet, and this may happen again. That is why researchers are constantly studying these objects, calculating their composition and trajectory. And if a dangerous space rock is rushing towards us, then it’s better to be prepared.
Asteroid Formation - Explained for Kids
Begin explanation for children It can be explained by the fact that asteroids are residual material from the formation of our system 4.6 billion years ago. When it was formed, it simply did not allow other planets to appear in the interval between itself and. Because of this, small objects there collided and turned into asteroids.
It is important that children understood this process, because scientists are diving deeper into the past every day. Recently, two theories have appeared: the Nice model and the Grand Tack. They believe that the gas giants traveled through the system before settling on their usual orbits. This movement could tear asteroids out of the main belt, changing its original appearance.
Physical characteristics of asteroids - explanation for children
Asteroids vary in size. Some can reach the volume of Ceres (940 km in width). If we take the smallest one, it was 2015 TC25 (2 meters), which flew near us in October 2015. But children may not worry, since asteroids have little chance of heading towards us in the near future.
Almost all asteroids formed in irregular shapes. Although the largest ones may approach the sphere. There are visible depressions and craters on them. For example, Vesta has a huge crater (460 km). The surface of most is covered with dust.
Asteroids also go around the star in an ellipse, so they make chaotic somersaults and rotations on their way. For the little ones It will be interesting to hear that some have a small satellite or two moons. There are binary or double asteroids, as well as triple ones. They are approximately the same size. Asteroids can evolve if a planet grabs them with its gravity. Then they increase their mass, go into orbit and turn into satellites. Among the candidates: and (Martian moons), as well as most of the moons of Jupiter, and.
They differ not only in size, but also in shape. They can be solid pieces or small fragments bound together by gravity. Between Uranus and Neptune there is an asteroid with its own ring system. And another one is endowed with six tails!
The average temperature reaches -73°C. They have existed virtually unchanged for billions of years, so it is important to study them to get a glimpse of the primitive world.
Classification of asteroids - explanation for children
The objects are located in three zones of our system. Most are grouped in a giant ring-shaped region between the orbits of Mars and Jupiter. This is the main belt, containing more than 200 asteroids with a diameter of 100 km, as well as from 1.1-1.9 million with a diameter of 1 km.
Parents or At school must explain to the children that not only asteroids of the solar system live in the belt. Ceres was previously considered an asteroid until it was reclassified as a dwarf planet. Moreover, not so long ago scientists identified a new class - “main belt asteroids”. These are small stone objects with tails. The tail appears when they crash, break up, or there is a hidden comet in front of you.
A lot of stones are located beyond the main belt. They gather near large planets in certain places (Lagrange point), where solar and planetary gravity are in balance. The largest number of representatives are the Trojans of Jupiter (in numbers they almost reach the size of the asteroid belt). Neptune, Mars and Earth also have them.
Near-Earth asteroids orbit closer to us than . Cupids come close in orbit, but do not intersect with the earth's. The Apollos intersect with our orbit, but most of the time they are located in the distance. Atons also cross the orbit, but are inside it. The atyrs are the closest. According to the European Space Agency, we are surrounded by 10,000 known near-Earth objects.
In addition to being divided by orbit, they also come in three classes of composition. C-type (carbonaceous) is gray and occupies 75% of known asteroids. Most likely, they are formed from clay and stony silicate rocks and inhabit the outer zones of the main belt. S-type (silica) – green and red, represent 17% of objects. Made from silicate materials and nickel-iron and predominant in the inner belt. M-type (metallic) – red and make up the rest of the representatives. Consist of nickel-iron. Certainly, children should know that there are many more varieties based on composition (V-type - Vesta, which has a basaltic volcanic crust).
Asteroid attack - explanation for children
4.5 billion years have passed since the formation of our planet and the fall of asteroids to Earth was a frequent occurrence. To cause serious damage to Earth, an asteroid would have to be ¼ mile wide. Because of this, such an amount of dust will rise into the atmosphere that it will form the conditions of a “nuclear winter.” On average, strong impacts occur once every 1000 years.
Smaller objects fall at intervals of 1000-10000 years and can destroy an entire city or create a tsunami. If the asteroid has not reached 25 meters, it will most likely burn up in the atmosphere.
Dozens of potential dangerous impactors travel in outer space and are constantly monitored. Some come pretty close, while others are considering the possibility in the future. To have time to react, there must be a reserve of 30-40 years. Although now there is more and more talk about technology to combat such objects. But there is a danger of missing the threat and then there simply will be no time left to react.
Important explain for the little ones that a possible threat also contains benefits. After all, once upon a time it was an asteroid impact that caused our appearance. When formed, the planet was dry and barren. Falling comets and asteroids left water and other carbon-based molecules on it, allowing life to form. During the formation of the solar system, objects stabilized and allowed modern life forms to take hold.
If an asteroid or part of it falls on a planet, it is called a meteorite.
Composition of asteroids - explanation for children
- Iron meteorites: iron (91%), nickel (8.5% ), cobalt (0.6%).
- Stony meteorites: oxygen (6%), iron (26%), silicon (18%), magnesium (14%), aluminum (1.5%), nickel (1.4%), calcium (1.3%) .
Discovery and name of asteroids - explanation for children
In 1801, a priest from Italy, Giuseppe Piazzi, was creating a star map. Quite by accident, between Mars and Jupiter, he noticed the first and large asteroid Ceres. Although today it is already a dwarf planet, because its mass accounts for ¼ of the mass of all known asteroids in the main belt or nearby.
In the first half of the 19th century, a lot of such objects were found, but all were classified as planets. It was not until 1802 that William Herschel coined the word "asteroid", although others continued to refer to them as "minor planets". By 1851, 15 new asteroids had been found, so the naming principle had to be changed, adding numbers. For example, Ceres became (1) Ceres.
The International Astronomical Union is not strict in naming asteroids, so you can now find objects named after Spock from Star Trek or rock musician Frank Happa. 7 asteroids were named after the Columbia crew who died in 2003.
The numbers are also added to them - 99942 Apophis.
Asteroid Research - Explained for Kids
The first close-up view of asteroids was taken by the Galileo spacecraft in 1991. In 1994, he also managed to find a satellite orbiting an asteroid. For a long time, NASA studied the near-Earth object Eros. After much deliberation, they decided to send the device to him. NEAR made a successful landing, becoming the first in this regard.
Hayabusa became the first vehicle to land and take off from an asteroid. He went in 2006 and returned in June 2010, bringing samples with him. NASA launched the Dawn mission in 2007 to study Vesta in 2011. A year later, they traveled from the asteroid to Ceres and reached it in 2015. In September 2016, NASA sent OSIRIS-REx to explore the asteroid Bennu.
Asteroids? First of all, I would like to say that this is the name given to rocky solid bodies that move in elliptical orbits around the Sun, like planets. However, space asteroids are much smaller in size than the planets themselves. Their diameter is approximately within the following limits: from several tens of meters to a thousand kilometers.
When wondering what asteroids are, a person involuntarily thinks about where this term even came from and what it means. It is translated as “star-like,” and was introduced in the 18th century by an astronomer named William Herschel.
Comets and asteroids can be seen as point sources of a certain light, more or less bright. Although in the visible range, data does not emit anything - it only reflects the sunlight that falls on it. It should be noted that comets are different from asteroids. The first is their different appearance. The comet is easily recognized by its brightly glowing core and the tail that extends from it.
Most of the asteroids that are known to astronomers today move between the orbits of Jupiter and Mars at a distance of approximately 2.2-3.2 AU. e. (that is, from the Sun. To date, scientists have discovered about 20 thousand asteroids. Only fifty percent of them are registered. What are registered asteroids? These are celestial bodies that have been assigned numbers, and sometimes even proper names. Their orbits have been calculated with very great accuracy. It should be noted that these celestial bodies usually have the names assigned to them by their discoverers. The names for asteroids are usually taken from ancient Greek mythology.
In general, from the above definition it becomes clear what asteroids are. However, what else is characteristic of them?
As a result of observations of these celestial bodies through a telescope, an interesting fact was discovered. The brightness of a large number of asteroids can change, and in a very short time - this takes several days, or even several hours. Scientists have long hypothesized that these changes in the brightness of asteroids are associated with their rotation. It should be noted that they are determined - first of all - by their irregular forms. And the first photographs that captured these celestial bodies (the photographs were taken with the help of this theory) confirmed this theory, and also showed the following: the surfaces of the asteroids are completely pitted with deep craters and craters of various sizes.
The largest asteroid discovered in our solar system was previously considered to be the celestial body Ceres, whose dimensions were about 975 x 909 kilometers. But since 2006 it received a different status. And it began to be called And the other two large asteroids (called Pallas and Vesta) have a diameter of 500 kilometers! Another interesting fact should also be noted. The fact is that Vesta is the only asteroid that can actually be observed with the naked eye.
